Dresden Unit 3 Automatically Shuts Down

Instrument power supply failure

MORRIS, Ill. (Oct. 11, 2010) - Dresden Generating Station Unit 3 automatically shut down at 10:04 a.m. today, as a result of an instrument power supply that failed. The plant responded as expected, safely and without incident.

Plant personnel will replace the instrument power supply, a mechanism that provides power to plant equipment, and then begin the start up procedures to return the unit to service.

The Dresden Unit 3 shutdown will not have an impact on electrical service to Exelon customers. Dresden Unit 2 continues to operate at full power.

Dresden Generating Station is approximately 60 miles southwest of Chicago. With both units running at full power, Dresden generates more than 1,700 megawatts net of electricity.

###

About Exelon

Exelon Corporation is one of the nation’s largest electric utilities with more than $17 billion in annual revenues. The company has one of the industry’s largest portfolios of electricity generation capacity, with a nationwide reach and strong positions in the Midwest and Mid-Atlantic. Exelon distributes electricity to approximately 5.4 million customers in northern Illinois and southeastern Pennsylvania and natural gas to approximately 486,000 customers in the Philadelphia area. Exelon is headquartered in Chicago and trades on the NYSE under the ticker EXC.